During epithelial tissue development, repair, and homeostasis, adherens junctions (AJs) ensure intercellular adhesion and tissue integrity while allowing for cell and tissue dynamics. Mechanical ...forces play critical roles in AJs’ composition and dynamics. Recent findings highlight that beyond a well-established role in reinforcing cell-cell adhesion, AJ mechanosensitivity promotes junctional remodeling and polarization, thereby regulating critical processes such as cell intercalation, division, and collective migration. Here, we provide an integrated view of mechanosensing mechanisms that regulate cell-cell contact composition, geometry, and integrity under tension and highlight pivotal roles for mechanosensitive AJ remodeling in preserving epithelial integrity and sustaining tissue dynamics.
During epithelial tissue development, repair, and homeostasis, adherens junctions (AJs) ensure tissue integrity while still allowing for cellular/tissue dynamics. Pinheiro and Bellaïche highlight recent work establishing AJ mechanosensitivity in junctional remodeling and provide an integrated view of mechanosensing mechanisms that regulate cell-cell contact composition, geometry, and integrity under tension.
During development, mechanical forces cause changes in size, shape, number, position, and gene expression of cells. They are therefore integral to any morphogenetic processes. Force generation by ...actin-myosin networks and force transmission through adhesive complexes are two self-organizing phenomena driving tissue morphogenesis. Coordination and integration of forces by long-range force transmission and mechanosensing of cells within tissues produce large-scale tissue shape changes. Extrinsic mechanical forces also control tissue patterning by modulating cell fate specification and differentiation. Thus, the interplay between tissue mechanics and biochemical signaling orchestrates tissue morphogenesis and patterning in development.
The orientation of the mitotic spindle has been proposed to control cell fate choices, tissue architecture, and tissue morphogenesis. Here, we review the mechanisms regulating the orientation of the ...axis of division and cell fate choices in classical models of asymmetric cell division. We then discuss the mechanisms of mitotic spindle orientation in symmetric cell divisions and its possible implications in tissue morphogenesis. Many recent studies show that future advances in the field of mitotic spindle orientation will arise from combinations of physical perturbation and modeling with classical genetics and developmental biology approaches.
To acquire their adequate size and shape, living tissues grow and substantially deform as they develop. To do so, the cells making up the tissue can grow and deform as well, but they can also divide, ...intercalate and die. Among those cell behaviors, cell intercalation, also named cell rearrangement, is a major contributor to the morphogenesis of many cohesive tissues since it enables tissues to drastically deform as they develop while keeping their cohesiveness and avoiding extreme deformation of their cells. Here we review the mechanical principles and biological regulations at play during cell rearrangements in Drosophila tissues by first describing them in other cellular materials and by categorizing them. We then briefly discuss their quantifications and their interplay with other cell processes.
Bosveld and Bellaïche discuss the composition and assembly of tricellular junctions, as well as their roles in cell packing, tissue mechanics and signalling.
As the result of an intricate interplay between mechanical and biochemical cues, coordinated cell dynamics are at the basis of tissue development, homeostasis and repair. Numerous studies have ...addressed the interplay between these two inputs and their impact on cellular dynamics. These studies largely focus on bicellular junctions (BCJs). Recent works have illuminated that tricellular junctions (TCJs), the junctions where three cells contact, play important roles in epithelial tissues beyond their well-known structural function in preserving epithelial barrier integrity. Indeed, TJCs have recently been implicated in the regulation of collective cell migration, division orientation, cell proliferation and cell mechanical properties. More generally, the TCJ distribution aligns with the cell shape and mechanical stress orientation within the tissue, while their number encapsulates the packing topology. Importantly, known regulators of growth signalling and of cell mechanical properties are also localized at TCJs. Therefore, TCJs emerge as spatial sites to sense and integrate biochemical and mechanical inputs to guide epithelial tissue dynamics.
Theoretical modeling is central to elucidating underlying principles of emergent properties of complex systems. In cell and developmental biology, the last 15 years have witnessed a convergence of ...empirical and modeling approaches for fresh perspectives. The role of cell division in coordinating size, shape, and fate in particular illustrates the ever-growing impact of modeling.
Theoretical modeling is central to elucidating underlying principles of emergent properties of complex systems. In cell and developmental biology, the last 15 years have witnessed a convergence of empirical and modeling approaches for fresh perspectives. The role of cell division in coordinating size, shape, and fate in particular illustrates the ever-growing impact of modeling.
Mitotic spindle orientation has been linked to asymmetric cell divisions, tissue morphogenesis and homeostasis. The canonical pathway to orient the mitotic spindle is composed of the cortical ...recruitment factor NuMA and the molecular motor dynein, which exerts pulling forces on astral microtubules to orient the spindle. Recent work has defined a novel role for NuMA as a direct contributor to force generation. In addition, the exploration of geometrical and physical cues combined with the study of classical polarity pathways has led to deeper insights into the upstream regulation of spindle orientation. Here, we focus on how cell shape, junctions and mechanical tension act to orient spindle pulling forces in epithelia, and discuss different roles for spindle orientation in epithelia.
Identifying the mechanisms that govern the precise sequence of tissue deformations and flows during development is a major topic in developmental biology. Recent studies have explored how the ...deformation or the flow of a tissue region can be induced by the activity of a neighboring region through mechanical coupling. Such a coupling process is akin to chemical induction, whereby differentiation in a region of competent cells is stimulated by a neighboring region through chemical induction: we therefore propose to name this phenomenon ‘mechanical induction’. Focusing on examples of mechanically induced epithelial flow or planar deformation in vivo, this review aims at discussing the processes driving mechanical induction and the competence factors modulating the induced morphogenesis, in order to highlight the importance of integrating tissue and inter-tissue scales to understand morphogenesis.
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